Evaluation of six commercial kits for the serological diagnosis of Mediterranean visceral leishmaniasis.

BACKGROUND: Zoonotic visceral leishmaniasis (VL) is endemic in the Mediterranean basin. However, large-scale comparative analyses of the commercial kits for the serological diagnosis of this neglected disease are lacking. This study compared the performances of four enzyme-linked immunosorbent assays (ELISA) and two immunochromatographic tests (ICT) as screening tests for the serodiagnosis of human VL in the Mediterranean region. METHODOLOGY/PRINCIPAL FINDINGS: Serum samples from 319 patients living in France, Tunisia or Morocco were tested using two ICT (IT LEISH and TruQuick LEISH IgG/IgM Meridian) and four ELISA reagents (NovaLisa Leishmania infantum IgG, Bordier Leishmania infantum, Ridascreen Leishmania IgG, and Vircell Leishmania). The population with proven VL (n = 181) included 65 immunocompromised patients. Significantly higher percentages of false-negative results were obtained with all assays in immunocompromised patients, compared with the immunocompetent population. In the whole population, sensitivity and specificity ranged from 80.7% to 93.9% and from 95.7% to 100%, respectively. The maximum accuracy was observed with the Bordier and Vircell ELISA kits (96.2%), and the lowest accuracy with Ridascreen reagent (88.7%). New thresholds of positivity are proposed for the Bordier, Vircell and NovaLisa ELISA kits to achieve 95% sensitivity with the highest possible specificity. Western blot (WB), used as a confirmation method, showed 100% sensitivity and identified 10.1% of asymptomatic carriers among the control population from the South of France. CONCLUSIONS/SIGNIFICANCE: This is the first study that compared commercially available kits for VL serodiagnosis in the endemic region of the Mediterranean basin. It provides specific information about the tests' performance to help clinicians and biologists to select the right assay for VL screening.

Place of Serology in the Diagnosis of Zoonotic Leishmaniases With a Focus on Visceral Leishmaniasis Due to Leishmania infantum.

Leishmaniases are a group of parasitic diseases transmitted through the bite of female phlebotomine sandflies. Depending on the Leishmania species, the reservoirs can be humans (anthroponosis) or different animals (zoonosis). Zoonotic leishmaniasis present several clinical forms in function of the species involved: visceral leishmaniasis (VL), cutaneous leishmaniasis (CL), and muco-cutaneous leishmaniasis (MCL). The biological diagnosis is of utmost importance because the clinical features are not specific. In addition to parasitological and molecular biology (polymerase chain reaction, PCR) assays, serology is routinely used for the diagnosis of leishmaniasis. Indeed, although PCR is more sensitive than serological assays, its implementation is limited to referral laboratories and research centers. Therefore, serology is still a key element for their diagnosis. Here, we discuss the different serological assays available for the diagnosis of zoonotic leishmaniasis. We will review the enzyme-linked immunosorbent assay, immunofluorescence antibody test, immunochromatography test (ICT), direct agglutination test, and western blot as well as the different diagnostic strategies in function of the clinical form (VL, CL, and MCL). We will also discuss the place of serology for detecting asymptomatic carriers and for the follow-up of VL. Depending on the laboratory, different assays can be used, from ICT, which is appropriate for field testing, to a combination of serological tests to improve the sensitivity.

Acquisition of enteric pathogens by pilgrims during the 2016 Hajj pilgrimage: A prospective cohort study.

BACKGROUND: Diarrhea can be frequent among Hajj pilgrims; however, data on its etiology are very limited. PATIENTS AND METHODS: A prospective cohort study was conducted among Hajj pilgrims in 2016. Medical follow-up and systematic rectal swabing were performed before leaving France and before leaving Saudi Arabia. Potential pathogens were identified using the BioFire FilmArray® Gastrointestinal multiplex qualitative PCR panel. RESULTS: 117 pilgrims were included and 13.7% experienced diarrhea during Hajj. Of the pre-Hajj samples, 32.5% were positive for at least one pathogen compared to 50% of post-Hajj samples (p = 0.0033). Diarrhea associated Escherichia coli strains, notably enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC), and Shiga-like toxin-producing E. coli, were acquired by 29.9%, 10.2%, and 6.5% pilgrims, respectively. Pilgrims with resolved diarrhea were significantly more likely to have post-Hajj EAEC positive samples, compared with those who did not suffer diarrhea (55.6% vs 16.5%). We found a lower prevalence of EPEC (22.5%) in pilgrims who declared washing their hands more frequently at the Hajj than usually as compared to others (40.0%). CONCLUSION: The acquisition of diarrhea associated E coli by Hajj pilgrims is of major concern given the high prevalence rate of third-generation cephalosporin-resistant E. coli in Saudi Arabia.